The goal of this project is to develop the first software specifically designed for the access, creation and visualization of environmental measures related to cancer health behavior and resources. This software, called METRIC for Measure of the Environment Targeted for Research In Cancer, will provide: 1) a user?friendly interface for locating, accessing and importing data into the existing Geographical Information System, 2) automated homogenization of data layers to a common geography, 3) flexible construction of metrics to characterize the food, physical activity and health care access environments, 4) visualization, exploratory data analysis and ranking of the results to identify geographical disparities, 5)uncertainty propagation and sensitivity analysis to assess the impact of metrics definition (e.g. weights of components, magnitude of measurement errors) on the robustness of indices and their relationship with health outcomes, and 6)efficient export of results into ESRI shapefile format, Excel workbooks and XML. The targeted user is the environmental epidemiologist or exposure scientist who lacks the technical expertise to automate access to diverse data resources from interactive and frequently updated web sources.